Tire construction



May 6, 1941. w. E. PHILLIPS TIRE CONSTRUCTION Original Filed Dec. 15, 1939 ular service on an, automobile;

Patented May 6, 1941 UNITED. STATES PATENT; QFFTCEN 2,240,856 I a e I Tmn coNsrR c'rIoNj Warren E. Phillips, Cuyahoga Falls, )hiojassignor H "to The B. F. Goodrich Company, Newy l N. Y a corporation of NewYork 3 Original application December 1939, Serial No. 309,369. Divided and this application'Decenn: bel'29,1939 ScrlalNo. 31:1,565

6 Claims. (01. 152-336) g a This invention relates totire constructions and Q particularly to so-calledwhite sidewall tires and other articles including a white' or other lightcolored rubber portion in closeproxilmity to other rubb'erportions which normally 'ordesirably contain materials which would stain, discolor or otherwise deleteriously affect the light colored portion. The inventionis particularly concerned with 'the provision or an improved construction for white sidewall tires designed tofpermit usein such tires of materials heretoforeprohibited and tentionally.

Considerable trouble has been encountered in producing an entirely satisfactory white, sidewall tire because whiteor other light-colored rubber compositions are subject to staining by a variety of migratory staining materials irequently'and bodied in tire constructions. Such. staining is especially serious ,when the .tire is exposed to sunlight for long periods as inthe courseoi reg For example, white rubber compositions are stained by almost all the common age-resistersnowavailableoornmercially for use in rubber; Many of thecommon accelerators oivul'canization soiteners, oils, and other common rubber compounding materidesirably employed in rubber compositionsem-p als likewise will stain white rubber. Materials contained by much ofthe ordinary reclaimed rubber and especially thatmadeiromold tires,

which is the main'source of scrap rubber, will s also stain I white rubber. The problem hereis particularly. complicated from the standpoint 'of controlling such staining because, in addition to staining oils frequently added during the re claiming process, the reclaimed rubber may contain a variety of moreor less indeterminatestaining materials carried overinto the reclaimed rubl-f her from the scrap rubber used in producing the reclaim. The precise composition of the scrap rubber and of thereclaimed rubber made from: it ordinarily is neither a known nor av constant lac:

tor but one which cannot be known precisely nor maintained without variance. Furthermore, all

such staining materials are soluble in rubber and will 'rnigratefrom'one rubber layer to another rubber layer contiguous to the first layer. 7

Ithasaccordingly not been feasible to use any such materials. either in the white rubbenconiposition itself or in any rubber composition ,dis-

posed closely adjacent to the white rubber in an is'tics favorable'to'thoroughrubberizing of cord fabric to be used in the carcass, it is desirable in manyinstances to utilize in therubber composition calendered on the cords a substantial proportion of reclaimed rubber prepared from, old. tires. Additionally, such use of reclaimed rubber in the carcass reduces the cost 'ofthe tire without lowering itsquality. This has notbeen possible in whitesidewall times without resultantstaining ofthesidewall, Similarly, it has not been possible to use inthe carcass comm on age-resisters, softeners and the like, and the choice Ioiaccelerators of vulcanization has been seriously limited by'these considerations. Evenwhen efforts are IllS dBtO eliminate all such migratory stain-, ing materials from the carcass, still staining of the white sidewall sometimes, results 'rrpm some unknown or unexpected staining material acci dentally or intentionally included in some of the adjacent rubber compositions.

serious staining difliculties hereinabove described and, additionally, makes possiblethe use of many materials heretofore prohibited in compositecon structionssuch' as white sidewall tires; with at tendant' substantial economies and definite iin provement in the quality of the productl" A tire construction embodyingthe invention is. illustrated in the accompanying drawing in which the single figure is a fragmentary sectional perspective view showing a portion of, a ti're ,embodying the invention, the sidewall portion bein stripped-back for clarity of illustration.

As illustrated, a tire construction embodying the present invention includes the usual bead portions l0, I0,carcass portion ll comprising-a plurality of plies of rubberized cord fabric, side- "Sulfur wall portions l2, I2, and a tread portion l3 which extends down over the shoulders of the tire to join the sidewall portions. As will be described more fully hereinafter, the sidewall portions 12, l2,"are formedcf a white rubbericomposition subject to staining'and the carcass portion ll comprises a rubber composition containing a migratory material which normally would migrate into and stain the white sidewall. Such migration and staining is prevented, however, by

Bufler layer rubber composition Parts by weight New crude rubber 100.0 Zinc oxide 5.0 Stearic acid 1.0 Sulfur 3.0 Accelerator (mercaptobenzo thiazole) 1.0 Migration inhibitor 30.0

'10 interposing buffer layers l4, between theside- 7 wall portions l2, I2 and the respective underly-- 'ing zones of the carcass portion II, the butterlayers l4, 14 being formed of arubber composi- 'tion containing a sufilcientfguantity of an inhibitor of migrationto check the migration effectively or to block it completely. Ordinarily, the buffer layer should contain from to 30 per cent byvolume of migrationinhibitor, the

percentage being-based on'the total rubber con- 'tent of the compositionfrom which the buffer layer is formed, Smaller 'or larger proportions 'of migration inhibitor may be used with some ,degree of satisfaction but quantities less than about' lO per cent by volume usually permit too much migration for practical success and quan tities' greaterthan about 30 per cent by volume are likely tomake'the buffer layer undesirably stiff. "I'he composition of the rubber in the tread Iandgbead portions is immaterial insofar as the presentfiinvention is concerned, since the area ofc'o'nta'ct between these portionsand the white The white sidewall rubber composition hereinabove set out will be stained and discolored, especially after prolonged exposure to sunlight, by

i a variety of materials including several of the f specific materials of the carcass rubber composition given above. 0f the carcass composition,

7 whole tire reclaimedrubber contains migrating staining materials of varying and somewhat indeterminate character. Likewise, pine tar, mineral rubber and the age-resister Neozone D a will stain thewhite sidewall.

.The migration inhibitor included in the rubber composition comprising the buffer layer may be sidewall ,is so slightthat, as a' practical'matte'r,

no problemof migration and staining is'in troducedi" "The tire, of course, isbuiltgup from its constituent parts and vulcanized in theusual manner to produce thefinishedtire in which the several parts jareiintegrallg united by conjoint yulca'nization'to provide ,auiiitary structure. 7.

Exemplary, recipes/for rubber COmDcsitions I satisfactory ior use in the sidewall and carcass portions of the tire and in the buffer layer interposed between them are [set out hereinbelow withoutint'ent to limit the invention thereto, it being-understood that the matei'ials specifled may" besubstituted or supplemented by numerous other'mat'erials and that all such materialsmay White sidewaZl.1 ubber composition b weie t Newcrude' rubber 100.0 Softeningagent ("Reogenf) ,7 0.5 Stearic.acid1 2.0 Pa

be used inwidely varying proportions, all accord- I v ing to' usual rubber compoundingpractice metres and I the like.

a resinous material such as ordinary animal glue, fish glue, rosin, shellac, 'cuinar resin, p-coumarone-indene' resin,.ester gum, vinyl resins, acrylic resins, alkyd resins, glyptal resins, phenol-formvbufier layer about 0.025" thick formed of such a composition will materially reduce the tendencyof the white'sidewall to stain when incorporated' in a the structure as described.

Thethermoprenes referred to in the preceding paragraph and specified in the appended claims are those artificial rubber isomers having less chemical unsaturation than rubber. Thermoprenes may be prepared by treating rubber with a variety ofisomerizmg agents (see Industrial and Engineering Chemistry, vol. 19, December 1927, page 1325 et seqJ, the most common oi which are sulfonic compounds having the formula R'SOzY--X wherein R represents an organic radical or a hy'droxy group and X represents a l hydroxy g oup. or chlorine (see U. s. Patent No. 1,605,180 granted November 2, 1926).

In order that the migration inhibitor may .function m'ostefl'ectively, the rubber composition ofv the bufier layer itself preferably should i be free of migratory staining materials when l the tire or other article is built. Small quantifgoited-in 'the'bufierlayer, however, and, in some ties of such materials are not absolutely prohib instances, considerable proportions of such materials may be present without destroying the eifective'ness 'of' the bufier layer.

' This application is a division of my co-pending' application SerialNo. 309,369 filed December 15, 19am Numerous modifications and variations in details of the'structures, materials, and'proportions claims.

of materials as hereihabove'described may be e1- 'fected without departing'irom-the' spirit and scope of theinve'ntion as defined by the appended Iclaiirif 3 r 1. An article of manufacture including a portion comprising a light-colored rubber composi- 4.0 tion normally subject to staining, a second porwould stain the light-colored composition, and a tion normally subject to staining, a second Dor tion disposed closely adjacent to the first portion and comprising a rubber composition containing a migratory material which normally would stain the light-colored composition, and a buffer layer interposed between the first two portions, the buffer layer comprising a rubber com-' unitary structure in which the light-colored first portion is not subject to staining by the migratory staining material of the second portion.

4. A tire casing comprising a light-colored sidewall portion normally subject to staining, a carcass portion comprising a rubber composition containing a migratory material which normally would stain the light-colored sidewall portion, and a buffer layer interposed between the lightcolored sidewall portion and the carcass portion,

said buil'er layer comprising a rubber composition position substantially free of staining materials tion comprising a light-colored rubber composi tion normally subject to staining, a second portion disposed closely adjacent to the first portion and comprising a rubber composition containing a migratory material which normally would stain the light-colored composition, and a buffer layer interposed between the first two portions, the

buffer layer comprising a rubber composition substantially free of staining materials and containing from 10 to 30 per cent by volume, basedon the rubber, of an inhibitor of migration comprising a thermoprene, the first and second portions being integrally united respectively with opposed faces of the buffer layer to provide a containing an inhibitor of migration comprising a thermoprene, whereby the light-colored sidewall portion is not subject to staining by the migratory staining material of the carcass portion.

5. A tire casing comprising a light-colored sidewall portion normally subject to staining, 2. carcass portion comprising a rubber composition containing a migratory material which normally would stain the light-colored sidewall portion, and a buffer layer interposed between the light-colored sidewall portion and the carcass portion, said buffer layer comprising a rubber composition substantially free of staining materials and containing an inhibitor of migration comprising a thermoprene, whereby the lightcolored sidewall portion is not subject to staining by the migratory staining material of the carcass portion.

6. A tire casing comprising a light-colored sidewall portion normallysubject to staining, a carcass portion comprising a rubber composition containing a migratory material which normally would stain the light-colored sidewall portion, and a butler layer interposed between the lightcolored sidewall portion and the carcass portion, said buffer layer comprising a rubber composition substantially free of staining materials and containing from 10 to 30 per cent by volume, based on the rubber, of an inhibitor of migration comprising a thermoprene, whereby the light-colored sidewall portion is not subject to staining by the migratory staining material of the carcass portion.

WARREN E. PHILLIPS. 

